1. Field of the Invention
The present invention relates to endothermic fuel generation systems and more particularly an endothermic fuel generation system for a propulsion producing engine that uses optical means for performing the chemical dissociation associated with so-called endothermic fuels.
2. Description of the Related Art
Purely thermodynamic means for the generation of endothermic fuels have long been used. Most fuels will dissociate into chemical radical constituents above a certain temperature. For example, if methanol is heated above 500xc2x0 F., it breaks down into a methyl group and a hydroxyl radical. When the fuels are broken into smaller chemical constituents, they are capable of drawing heat from a body. This is extremely useful, for example, in high speed flight where wing surfaces must be cooled to prevent them from melting.
However, raising the temperature of a fuel to break it down is impractical since most fuels are kept cold to enhance their heat removal properties. An alternate means to dissociate the fuel molecule is to pass it through a catalyst. When a methanol molecule, by way of example, resides on a silver metal surface, the molecule will break down into the same radicals that result from heating. So, passing methanol through a silver catalytic bed will produce endothermic fuel at a low temperature.
However, catalytic beds have their own deficiencies. They are, by nature, heavy, bulky, difficult to flow through and subject to their own chemical and mechanical breakdowns.
U.S. Pat. No. 4,702,808, issued to J. H. Lemelson, entitled xe2x80x9cChemical Reaction Apparatus and Methodxe2x80x9d discloses rocket engine ignition in which propellants are ignited by an intense radiant energy, such as a light beam generated by a laser mounted in a housing. A beam of intense light is directed to the interior volume and caused to intersect fuel fed through inlets to effect ignition. There is no discussion in this patent of the photo-chemical interaction between the light and the fuel.
U.S. Pat. No. 5,727,368, issued to E. J. Wernimont, entitled xe2x80x9cHybrid Motor System with a Consumable Catalytic Bed a Composition of the Catalytic Bed and a Method of Usingxe2x80x9d, discloses a method, device, and composition for achieving ignition and sustained combustion using a solid consumable catalytic bed. The consumable catalytic bed (CCB) accomplishes this by decomposition of an injected fuel. Initially, this reaction is catalytic or hypergolic)in nature eventually becoming entirely thermal as the CCB is consumed in the reaction generated. The patent is directed to a hydrogen peroxide hybrid rocket. The catalytic bed is divided for the purpose of generating ignition and does not create an endothermic fuel before introduction into the fuel chamber.
Present applicants are the inventors of U.S. Pat. Ser. No. 09/471,540 filed on Dec. 23, 1999, entitled: xe2x80x9cIgnition System For A Propulsion Producing Enginexe2x80x9d. In that patent application, the inventors discussed an optical means for initiating combustion in a propulsion producing engine which uses peroxide as an oxidizer in the combustion reaction.
It is therefore a principal object of the present invention to provide an optical means to generate endothermic fuel for use in a propulsion producing engine.
Another object is to use an optical system as a means for disassociating the fuel.
These and other objects are achieved by the present invention, which in its broadest aspects, includes an optical source capable of producing light having physical characteristics sufficient for optically driven chemical disassociation of a fuel; and, an optical delivery system for providing optical delivery of light from the optical source to a chemical fuel source. The optical system is used for a propulsion producing engine having a chemical fuel source. The endothermic fuel generation is produced by the nonlinear, optical interaction of the produced light with the fuel, thereby leading to molecular dissociation of the fuel.
The use of optically induced endothermic fuel generation in a propulsion producing engine has advantages over standard endothermic fuel generation systems. Heating the fuel to break it into molecular constituents is impractical since fuel usually has the additional task of cooling the engine and/or airframe. If the fuel is hot, this capability is reduced. The standard endothermic fuel production means for most engines is a solid silver catalyst. The metal catalyst which holds the silver metal surface is large, heavy and must be located within the high speed flow between the fuel source and combustion chamber. Consequently, remote location is not possible. In addition to increased weight and volume, introduction of a catalyst in the fuel flow line causes pressure reduction, turbulence and reduced flow speeds. Optical fuel dissociation can be affected at any temperature, and the introduction of the light does not impinge on the fuel flow properties. The optical system can be located remotely and does not add the weight of a metal catalyst. Thus, the optical fuel dissociation leads to lighter weight engines.
These and other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.